1. Filed of Invention
The present invention relates to power converters, and more particularly, to the switching control circuit of power converters.
2. Description of Related Art
The high current demand normally decreases the power efficiency in the power converter. The power loss of the power converter is exponentially proportional to its current.PLOSS=I2×R  (1)where I is a switching current of the power converter, R is the impedance of the switching devices such as the equivalent resistance of the inductor and the transistor, etc.
Therefore, parallel technologies are developed for reducing the power consumption of power converter. The PFC (power factor correction) power converter is utilized to improve the power factor of AC power source. The detail skill of the PFC circuit can be found in prior arts, such as U.S. Pat. No. 7,116,090 “Switching control circuit for discontinuous mode PFC converters”.